It is conventional to test the integrity of soldered pin connections of IC components with traces on a circuit board and the like by mounting such boards in a test fixture and positioning test heads of various types in overlying, closely adjacent relationship to the components to be tested. A typical circuit board to be tested has anywhere from 20 to 40 or more test heads which must be mounted in very precise locations relative to the components to be tested in the X, Y and Z axes, i.e., in three directions perpendicular to one another. For example, when using vectorless testing techniques, such as a magnetic inductive test or capacitive coupling test, the test head, comprising a magnetic inducer or a capacitive probe respectively, is placed directly over the component under test and positioned no more than a selected distance, such as 0.010-0.020 inches from the component. As seen in FIG. 1, each test head (1) is mounted on a bracket 4 which is suspended from any one of a plurality of rails 2 movably mounted in an X direction (slots 6) over the mounting surface and circuit board CB mounting the component. The bracket typically is adjustably attached to the rail in the Y and Z directions by using one or more screw members 5. Due to the precise locating requirements of the test head, it is not unusual for a skilled technician to take the better part of a man-day to complete a typical set-up. A common time consuming problem occurs when an adjustment to the position of one of the heads must be made after a test set up has been largely completed. In order to get at the screws of the test head to be adjusted, an adjacent rail may have to be moved due to spatial limitations causing the heads on that rail to move out of position thereby adding to the already long set up-time to thereafter reposition the test heads.